1. Field of the Invention
The present invention relates to a voltage non-linear resistor comprising, as its main ingredient, zinc oxides and more particularly a voltage non-linear resistor which has stable electric characteristics such as a lightning discharge current withstanding capability.
2. Description of the Prior Art
A voltage non-linear resistor comprising zinc oxides as its main ingredient and a little amount of Bi.sub.2 O.sub.3, Sb.sub.2 O.sub.3, SiO.sub.2, Co.sub.2 O.sub.3, MnO.sub.2 etc. as its additive ingredient has been heretofore known as showing an excellent voltage non-linearity. Therefore, the voltage non-linear resistor is widely utilized in arrestors etc.
Since the voltage non-linear resistor have characteristics of acting as an insulator usually but as a conductor when an overcurrent flows, a line accident due to a thunderbolt can be effectively prevented even when the thunderbolt strikes the arrestor utilizing the voltage non-linear resistor.
In a voltage non-linear resistance element of the voltage non-linear resistor mentioned above, when a surge current such as thunderbolts etc. is applied to the element, a lightning discharge mainly along a peripheral side surface of the element i.e. flashover occurs and the resistor is liable to be broken. Therefore, it is necessary to arrange a high resistance layer onto a peripheral side surface of the element. However, the flashover can not be effectively prevented corresponding to a structural state of the high resistance layer even though the high resistance layer is arranged, because the occurrence of flashover is largely dependent upon the structural state of the high resistance layer. That is to say, in the high resistance layer comprising a zinc silicate phase consisting mainly of Zn.sub.2 SiO.sub.4 and a spinel phase consisting mainly of Zn.sub.7 Sb.sub.2 O.sub.12, particle states of respective phases especially zinc silicate phase is largely dependent upon the prevention of flashover, so that, as the case may be, the flashover can not be effectively prevented.